Alcohols nickel catalyst

Scheme 2.23 Conjugate addition of diethylzinc to enones with an in situ generated ferrocenylaziridine nickel catalyst, an in situ generated amino amide nickel catalyst, and an in situ generated 1,3-amino alcohol nickel catalyst.

Scheme 2.24 Conjugate additions of diethylzinc to chalcones and cyclohex-2-enone with an in situ generated aziridine sulfoxide nickel catalyst and an in situ generated aziridine alcohol nickel catalyst.

Piperitone is of considerable technical im portance. It is a colourless oil of a pleasant peppermint-like smell. (-)-Piperilone has b.p. 109-5-110-5 C/I5mm. Piperitone yields thymol on oxidation with FeCl. On reduction with hydrogen in presence of a nickel catalyst it yields menthone. On reduction with sodium in alcoholic solution all forms of piperitone yield racemic menthols and womenthols together with some racemic a-phel)andrene. 

P-Phenylethylamine is conveniently prepared by the hydrogenation under pressure of benzyl cyanide with Raney nickel catalyst (see Section VI,5) in the presence of either a saturated solution of dry ammonia in anhydrous methyl alcohol or of liquid ammonia the latter are added to suppress the formation of the secondary amine, di- P phenylethylamine ... 

Tetrahydrofurfuryl alcohol reacts with ammonia to give a variety of nitrogen containing compounds depending on the conditions employed. Over a barium hydroxide-promoted skeletal nickel—aluminum catalyst, 2-tetrahydrofurfur5iarnine [4795-29-3] is produced (113—115). With paHadium on alumina catalyst in the vapor phase (250—300°C), pyridine [110-86-1] is the principal product (116—117) pyridine also is formed using Zn and Cr based catalysts (118,119). At low pressure and 200°C over a reduced nickel catalyst, piperidine is obtained in good yield (120,121). 

The reduction of nitro alcohols to alkanolamines is readily accompHshed by hydrogenation in the presence of Raney nickel catalyst (1,9,10). 

Two different sets of experimental conditions have been used. Buu-Hoi et al. and Hansen have employed the method introduced by Papa et using Raney nickel alloy directly for the desulfurization in an alkaline medium. Under these conditions most functional groups are removed and this method is most convenient for the preparation of aliphatic acids. The other method uses Raney nickel catalysts of different reactivity in various solvents such as aqueous ammonia, alcohol, ether, or acetone. The solvent and activity of the catalyst can have an appreciable influence on yields and types of compounds formed, but have not yet been investigated in detail. In acetic anhydride, for instance, desulfurization of thiophenes does not occur and these reaction conditions have been employed for reductive acetylation of nitrothiophenes. Even under the mildest conditions, all double bonds are hydrogenated and all halogens removed. Nitro and oxime groups are reduced to amines. 

The hydrogenation of pyrazolylacetylenes shows no peculiarities. Ethynylpyra-zoles are hydrogenated in high yields to the corresponding ethane derivatives on Raney nickel catalyst, platinum dioxide, or palladium catalyst at room temperature in alcohol solution. 

This hydrochloride, on being dissolved in water and hydrogenated with hydrogen and a nickel catalyst, gave a good yield of hydrochloride of hydroxy-4 -phenyl-1-amino-2-ethanol melting, after crystallization from a mixture of ethyl alcohol and butanone-2, at from 177° to 179°C with decomposition. 

Lauryl Alcohol (to, 62) By the reduction of ethyl laurate at 260° over a nickel catalyst. Palfray and Sabctay, Bull. soc. chim. (5) 3, 682 (1936). 

Neopentyl alcohol, 40, 76 Nickel catalyst for hydrogenation of resorcinol, 41, 56, 57 Nitramines from amines and acetone cyanohydrin nitrate, 43, 84 Nitration, of amines to nitramines by acetone cyanohydrin nitrate, 43, 83... 

As shown in this table, the metal catalysts used in the literature are mostly complexes of Ni or Cu and less often Co or Pd. For soft nucleophiles, on the left of the table, the efficiency of the nickel catalysts was already reported. Here, are presented the investigations concerning the arylation of hard nucleophiles such as amines, alcohols or hydroxide anion, using Ni, Pd and Cu catalysts. 

Therefore, for the arylation of oxygenated nucleophiles, particularly of the alcohols, the investigations were focused on the nickel catalysts (Fig. 8). 

The comparison of several nickel catalyst for the arylation of alcohols with arylbromide has been performed, in the same conditions of time, temperature and base, using different oxygen, phosphorus and nitrogen ligands. The yields for each catalyst, shown in the table (Fig. 9) range from 5 to 80 %. 

These results point out, for the arylation of alcohols, a better activity of the nickel catalysts in comparison to the copper analogs. That might be probably connected to the harder character of nickel(II) complexes in comparison to the copper analogs. 

A new comparison of the copper and nickel catalysts (Fig. 12) on the arylation of alcohols, using potassium carbonate as base, shows once again the superiority of the nickel catalyst (70 % against 40 % for the copper catalyst). 

This reaction is similar to 13-1 and, like that one, generally requires activated substrates. With unactivated substrates, side reactions predominate, though aryl methyl ethers have been prepared from unactivated chlorides by treatment with MeO in HMPA. This reaction gives better yields than 13-1 and is used more often. A good solvent is liquid ammonia. The compound NaOMe reacted with o- and p-fluoronitrobenzenes 10 times faster in NH3 at — 70°C than in MeOH. Phase-transfer catalysis has also been used. The reaction of 4-iodotoluene and 3,4-dimethylphenol, in the presence of a copper catalyst and cesium carbonate, gave the diaryl ether (Ar—O—Ar ). Alcohols were coupled with aryl halides in the presence of palladium catalysts to give the Ar—O—R ether. Nickel catalysts have also been used. ... 

The first palladium-catalyzed formation of aryl alkyl ethers in an intermolecular fashion occurred between activated aryl halides and alkoxides (Equation (28)), and the first formation of vinyl ethers occurred between activated vinyl halides and tin alkoxides (Equation (29)). Reactions of activated chloro- and bromoarenes with NaO-Z-Bu to form /-butyl aryl ethers occurred in the presence of palladium and DPPF as catalyst,107 while reactions of activated aryl halides with alcohols that could undergo /3-hydrogen elimination occurred in the presence of palladium and BINAP as catalyst.110 Reactions of NaO-/-Bu with unactivated aryl halides gave only modest yields of ether when catalyzed by aromatic bisphosphines.110 Similar chemistry occurred in the presence of nickel catalysts. In fact, nickel catalysts produced higher yields of silyl aryl ethers than palladium catalysts.108 The formation of diaryl ethers from activated aryl halides in the presence of palladium catalysts bearing DPPF or a CF3-subsituted DPPF was also reported 109... 

In several separate small scale experiments, It was noted that the coupling reaction was not impeded by adding pyridine, triethylamine, t-butyl alcohol, chlorotrimethylsilane, or diisopropylamine to the reaction mixture before adding the nickel catalyst. These results suggest that a variety of functional groups can be present in the enone partner of the coupling reaction. In addition toluene can be used instead of tetrahydrofuran as the solvent. 

These telomerization reactions of butadiene with nucleophiles are also catalyzed by nickel complexes. For example, amines (18-23), active methylene compounds (23, 24), alcohols (25, 26), and phenol (27) react with butadiene. However, the selectivity and catalytic activity of nickel catalysts are lower than those of palladium catalysts. In addition, a mixture of monomeric and dimeric telomers is usually formed with nickel catalysts ... 

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